This invention relates to a system, a method, and a computer that accomplish quick switching between computers in the event of a failure in a computer system where clusters are built.
A cluster system which includes an active server for executing a service and an auxiliary server which takes over the service in the event of a failure is used to secure the availability of a computer system. Cold standby systems are known as one of cluster systems of this type.
A cluster system stores data necessary for the execution of a service in at least one of an external storage system and an internal storage device which is provided in a server.
In the case where the data is stored in the storage system, the active server and the auxiliary server are both coupled to the same storage system via a storage area network (SAN). Normally, a communication path is established between the active server and the storage system, and the active server uses the data stored in the storage system to execute the service.
Cluster systems that use a storage system are employed in systems that place importance on reliability, and cluster systems that use an internal storage device are employed in systems that place importance on price.
In the event of a failure in the active server, the two methods described above switch from the active server to the auxiliary server as follows.
A cluster system that uses a storage system switches from a communication path between the active server and the storage system to a communication path between the auxiliary server and the storage system. A cluster system that uses an internal storage device obtains backup data of data stored in the internal storage device of the active server, and restores the backup data to the internal storage device of the auxiliary server.
The switch from the active server to the auxiliary server is made by various known methods (see, for example, Japanese Patent Application Laid-open No. 2009-129148).